Cities have taken leadership roles in environmental issues like reducing greenhouse gas emissions and air and water pollution for some time, now. But they really took the spotlight in 2015, and city-focused philanthropists are urging them to expand their influence.

For much of modern history, urban settings were seen as enemies of the environment, with out-of-control industry degrading air, water, and surrounding wilderness. But as Laura Bliss points out in CityLab, in the past decade or so, municipal leaders have become environmental heroes.

As the population grows and becomes more urban, and our views on density and sprawl evolve, we’re coming around to the fact that sustainability—and most notably, climate change—will be won or lost in cities.

This shift has been happening for years now, but 2015 felt like a pivotal moment for the city as an environmental hero, with mayors taking the spotlight during COP21 talks in Paris.

Philanthropy has been a contributing force in many of the initiatives that are pioneering emissions reductions and other sustainability measures. I’ll get into some of the reasons why this is such a ripe opportunity for funders, but first here are some highlights from the year.

Special Envoy Bloomberg & Co.

We wrote a lot about Mike Bloomberg and his philanthropic team in 2015, and while his ongoing war on coal is probably his most notable environmental endeavor, he also took a number of steps to elevate city leaders. Bloomberg kicked off the year by giving $24 million, matched by the Heising-Simons Foundation, to help states and cities speed the transition to clean energy. While not exclusively environmental, the $42 million What Works Cities initiative will also help cities use data to solve local problems.

Bloomberg, of course, has been promoting the role of cities in curbing climate change for years, pushing policies as mayor of New York City that reduced the city's carbon footprint. He also served as chairman of the C40 Cities Climate Leadership Group, a network of the world’s biggest cities collaborating to reduce carbon emissions. He's also been a major donor to that group. Bloomberg was a prominent voice during the COP21 talks in Paris, as U.N. special envoy for cities and climate change. Bloomberg Philanthropies, Kresge, and Doris Duke also announced at the talks a $10.5 million pledge for city building efficiency.

Rockefeller and Kresge Stay Resilient

The Rockefeller Foundation continues to be a leader in supporting cities’ efforts to address climate change, with a particular interest in resiliency. The funder launched its 100 Resilient Cities Challenge a few years back, and in 2015, increased funding for the initiative by $64 million. One of the most interesting aspects of the program is that it goes so far as to fund full-time city employees in selected locations.

Kresge is also a champion of resiliency projects, especially as it relates to justice and supporting low-income communities. The funder recently pledged almost $8 million to "bolster the capacity of community-based nonprofit groups" to influence local and regional climate resilience policies "in ways that better reflect the needs of underrepresented people in U.S. cities."

Paul Allen’s War on Traffic

Allen’s Vulcan Inc. recently partnered with the U.S. Department of Transportation, giving $10 million to the feds’ $40 million for a “Smart City” competition to “re-imagine how people move.” While it’s been framed as a competition to combat traffic jams and accidents, make no mistake—this is an environmental initiative. Allen is motivated by a desire to reduce greenhouse gas emissions, and competitors will almost certainly explore better mass transit and land use policy.

Smaller Funders Take the Lead

We saw several small- to medium-sized funders approaching global environmental problems through urban solutions. One of our favorite foundations working in this space is Surdna, which has put a stake in the ground in city infrastructure issues. Led by Helen Chin, who has a background in urban environmental policy, Surdna’s program increase the sustainability and equity of water, food, transportation, and energy systems. One interesting component is an initiative to give local communities more democratic control over their energy systems.

But Surdna’s not alone. Seattle’s Bullitt Foundation has an Urban Ecology program that kicked off an initiative in 2015 to expedite development of supergreen buildings. The Pisces Foundation ramped up its giving, including funding to improve water systems in select cities using green infrastructure. The Bay Area’s Lisa and Douglas Goldman Fund has been delving into transit and land use issues. Several other city-focused foundations have similar environment- and climate change-related programs to ease local impacts. Most notably, the Barr Foundation is channeling its concerns on climate change into ambitious sustainability efforts in Boston.

This embrace of urban environmentalism is a natural one for funders, for a handful of reasons.

The biggest draw is that, when faced with problems as daunting as mass extinction, rising sea levels and deforestation, retooling a city offers funders a realistic route to making environmental impact. You don't need a divided U.S. congress to go along, much less China.

There’s a bang-for-the-buck factor, in that funders can focus on a relatively small, densely populated region with a large carbon footprint or pollution problem, and leverage big payoffs with the right investment. And those payoffs will likely be measurable, something we all know funders are obsessed with.

For local funders, including community foundations and wealthy families, there’s also a sense of local affinity that goes hand in hand with that tangibility. They can take pride not only in reducing their city’s carbon footprint, but also in making their hometown a national leader.

Finally, there’s the fact that city governments are often more politically amenable to addressing environmental issues. They evade partisan divisiveness, often due to greater ideological alignment, but also the fact that they have to live with their political decisions every day.

Municipal leaders need solutions, they need money, and they need champions on the issues. A savvy funder can plug right into those roles.

That’s not to say all of this is easy. The increasing coziness of private funders and cities, with many of them even appointing liaisons for foundations, opens up all sorts of pitfalls. We’ve written extensively about equity issues with parks. Shifting demographics create the danger of a “beautifully sustainable city that is the playground of the rich.” There are also concerns about undue influence over candidates and public processes.

Environmental city philanthropy shows huge potential and is only going to increase, but the challenge going forward will beensuring that it’s facilitating local democracy and not subverting it.